Spindle assembly for a spinning or twisting machine



June 24, 1969 F@ STAHLECKER 3,451,135

SPINDLE ASSEMBLY FOR A SPINNING OR TWISTING MACHINE -v Filed 001;."18, 1967 sheet l of s INVENTOR ATTORNEYS June 24, 1969 F. STAHLECKER SPINDLE ASSEMBLY FOR A SPINNING OR TWISTING MACHINE Filed oct. 18, 19e? sheet L of 5 y 591 57a 14% 54 w,

l 58 um e s 5k' 57am) INVENTOR BY @MQW/M' ATTORNEYS United States Patent O 3,451,735 SPINDLE ASSEMBLY FOR A SPINNING R TWISTING MACHINE Fritz Stahlecker, Wurttemberg, Germany, assigner to Spindelfabrik Sussen, Schurr Stahlecker & Grill G.m.b.H., Wurttemberg, Germany Filed Oct. 18, 1967, Ser. No. 676,185 Claims priority, application Germany, Dec. 1, 1966, S 107,208; Aug. 16, 1967, S 111,373 Int. Cl. F16c 35 /08 U.S. Cl. 308-150 25 Claims ABSTRACT 0F THE DISCLOSURE A spindle assembly for a spinning or twisting machine, wherein the lower end of the center shaft runs in a pivot bearing which is mounted in the bearing housing separately from the upper collar bearing and is held in radial directions within the housing by a tubular, radially resilient connecting element in the form of a basket spring and in the axial direction by a supporting plug which is inserted into the lower end of the housing. In one preferred embodiment of the invention, a convex bearing plate or a ball bearing is interposed between this plug and the pivot bearing, while in another embodiment the pivot bearing itself is divided into a bearing plate for taking up the axial forces and a bearing sleeve for taking up the radial pressures of the lower end of the center shaft.

The present invention relates to a spindle assembly for a spinning or twisting machine wherein the lower end of the center shaft runs in a pivot bearing which is mounted in the bearing housing separately from the upper collar bearing so as to be radially movable by being supported in the downward direction either directly on a supporting element which is inserted into the housing or through a bushing which surrounds the pivot bearing, and wherein this pivot bearing is provided with suitable 'vibration damping means.

While spindles of the above mentioned type which are provided with vibration damping means `are generally known, these known constructions have at least partly the disadvantage that depending upon the dimensions of the supporting means the vibrations of the center shaft are either insuficiently damped or the center shaft is insuiciently centered. These known constructions have the further disadvantage that for damping strong vibrations which occur within or adjacent to critical ranges they require additional damping means.

`Other spindle constructions of known types have the disadvantage that the pivot bearing which is guided so as to be radially movable may easily become jammed which leads to excessive friction and prevents the center shaft from being accurately and reliably centered. -In still other -known spindle constructions, the centering effect is attained by means of a centering sleeve which is provided with tilting edges either above or below the pivot bearing. These last spindle constructions have the disadvantage that the centering action does not occur as smoothly and reliably when the individual spindle components are not very accurately made or when their functions are impaired by wear.

It is an object of the present invention to provide a pivot bearing assembly for the center shaft of a spindle which is designed so as to eliminate the above-mentioned disadvantages of the known spindle constructions, especially those concerning the centering properties thereof, and which by the use of very simple and reliable means insures a good opearting characteristic and a smooth run of the center shaft even though the spindle is subjected ice to very high stresses, and prevents the occurrence of dangerous vibrations.

For attaining this object, the invention consists in providing a tubular connecting element which is radially resilient along a part of its length and preferably serves for centering the pivot bearing, and in guiding this connecting element radially on the supporting element and on the pivot bearing or on a bushing which surrounds the pivot bearing. One part of the connecting element is preferably rigidly secured to .a supporting plug which is mounted in the housing, while its other radially resilient part guides the pivot bearing or its bushing. This arrangement may also be reversed so that one part of the connecting element is rigidly secured to the pivot bearing or its bushing, while the other resilient part is guided on the supporting plug. The connecting element may in this manner be mounted so as to guide the pivot bearing very accurately and with a certain clearance, if desired, and this may be attained by making the connecting element of a very simple design in the form of a cylindrical or conical tubular member. For attaining a very favorable operating characteristic of the spindle, it has been found advisable to provide an intermediate member within the connecting element between the supporting surface of the supporting element and the lower end of the pivot bearing and to make this member of a slightly smaller outer diameter than the inner diameter of the connecting element so as to have a small amount of play within the connecting element.

According to the invention it has further been found that the operating characteristic especially of heavy spin dles which are affected by the wear on the pointed lower end of the center shaft and on the bearing surface of the pivot bearing and also by the sliding friction occurring between the lower plane end surface of this bearing and the supporting surface of the supporting element may be further improved considerably by dividing this bearing into a bearing plate which takes up the .axial pressure of the center shaft and a bearing sleeve which is movable independently of the bearing plate and takes up the radial pressures of the center shaft, and by guiding the connecting element radially on the bearing sleeve or on a bushing surrounding the same. When the pivot bearing assembly is made of such a construction, the end surface of the rotating center shaft carries out circular, elliptical or similar movements on the bearing plate which is nonrotatable or only rotates very slowly. These movements are not affected by any pivoting movements of the pivot bearing or by inaccurately made bearing surfaces of the pivot bearing and the supporting element as may occur in onepiece pivot bearings. These circular movements also produce less friction than lthe sliding movements of the known nonrotatable pivot bearings. The frictional forces which occur on the lower contact `surface of the bearing sleeve are very small since the bearing sleeve is not affected by axial pressures which are exerted by the center shaft.

The features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which:

FIGURE l shows a longitudinal section of a bearing housing of a spindle in which the center shaft is supported by a pivot bearing which is rigidly secured within a bushing and projects downwardly into a connecting element in the form of a basket spring which is mounted on a plug which supports the pivot bearing through an intermediate plate-shaped element and also forms the bottom closure of the bearing housing, and wherein an oil-immersed coil is interposed between the bushing and the wall of the bearing housing;

FIGURE 2 shows an elevation of a basket spring as employed in the assembly according to FIGURE I;

FIGURE 3 shows a cross section which is taken along the line III-III of FIGURE 2;

FGURE 4 shows an elevation of a basket spring similar to that according to FGURE 2, but wherein the spring tongues when in the released condition are conically inclined toward the upper end of the spring;

FIGURE 5 shows a longitudinal section of a pivotbearing assembly according to a modification of the assembly as shown in FIGURE l, in which the intermediate element between the pivot bearing and the supporting plug is provided in the form of a plate with convex surfaces;

FIGURE `6 shows a longitudinal section of a pivotbearing assembly according to another modification, in which the intermediate element is provided in the form of a ball;

FIGURE 7 shows a longitudinal section of another modification of the pivot-bearing assembly in which the intermediate element is provided in the form of a ball bearing including a ball cage;

FIGURE 8 shows a top view of the ball bearing according to FIGURE 7;

FIGURE 9 shows a longitudinal section of another modification of the pivot-bearing assembly in which the supporting plug does not also serve as a bottom closure of the housing but is built into the housing, and in which a basket spring is secured to the wall of the housing;

FIGURE 10 shows a longitudinal section of another modification of the pivot-bearing assembly in which the tongues of the basket spring are extended upwardly and the supporting plug is fianged into the housing;

FIGURE 1l shows a longitudinal section of another modification of the pivot-bearing assembly in which the basket spring is secured to the pivot bearing and the downwardly extending spring tongues grip the supporting plug;

FIGURE 12 Shows a part of a longitudinal section of a further modification of the pivot-bearing assembly in which the connecting element consists of plastic;

FIGURE 13 shows a longitudinal section of a further modification of the pivot-bearing assembly in which the pivot bearing is guided with a small radial play in a socketlike bushing which, in turn, is supported on a bearing plate, and in which the basket spring is provided with radially resilient tongues embracing the bushing and with arms for supporting a damping sleeve or the like;

FIGURE 14 shows a longitudinal section of a further modification of the pivot-bearing assembly in which the pivot-bearing is divided into a bearing plate resting directly on the supporting plug and a bearing sleeve surrounded by an oil-immersed coil and prevented by a separate bushing from turning within the housing and from shifting in the upward direction;

FIGURE l5 shows a cross section which is taken along the line II-II of FIGURE 14 and in which the oil-immersed coil is omitted;

FIGURE 16 shows a longitudinal section of the left half of an assembly similar to that according to FIGURE 14, but provided with a resilient member interposed between the bearing plate and the supporting plug and with a bushing surrounding the bearing sleeve;

FIGURE 17 shows a longitudinal section of the left half of another assembly similar to that according to FIGURE 14, but provided with a bearing plate forming an integral part of the supporting plug; while FIGURE 18 finally shows a longitudinal section of the left half of an assembly similar to that according to FIGURE 14, but provided with a bushing which surrounds the bearing sleeve with a small intermediate clearance, rests on the supporting plug, and guides the basket spring.

As illustrated in FIGURE 1, the center shaft 1 of the spindle is rotatably mounted in a collar bearing 2 in the form of a roller bearing within the upper end of the bearing housing 3, While the lower end of the center shaft is mounted in a pivot bearing 4 which is secured in a bushing 5, the upper part of which is provided with slots 5a through which a guard ring 5b extends which is clamped to the wall of the housing 3 and thus prevents the bushing 5 from rotating. The pivot bearing `4 rests on a hardened disk 7 which, in turn, rests on a supporting plug 6. This supporting plug 6 which forms a turned part has a stepped fiange 6a which serves as a cap for closing the tubular housing 3a and is fitted into the housing and then welded thereto so that its cylindrical outer surface is accurately in alignment with the adjacent part of housing 3. The supporting plug 6 and the connecting element 8 which is guided thereby and provided in the form of a basket spring are thus maintained in an accurate central position within the housing.

The supporting plug 6 is provided with a radial recess 6b which divides the outer cylindrical surface of the plug into the two parts 6c and 6d, and with a further groove 6e between the liange 6a and the part 6d. Basket spring S, as shown particularly in FIGURES 2 and 3, which is bent by rolling of a piece of spring plate and has an open side wall fits tightly upon the part 6d of the supporting plug and is prevented from shifting in the axial direction by a small inwardly stamped locking tab 8a which engages into the groove 6e. The resilient tongues 8b of this spring engage upon the cylindrical part 6c of the supporting plug and their ends surround the pivot bearing 4 with a small clearange (not shown) and are therefore not under tension. The intermediate disk 7 rests with a small radial clearance within the basket spring 8.

Between the tubular bushing 5 and the inner wall of the bearing housing 3 a damping element is mounted which may consist, for example, of a spirally wound coil 9 which is immersed in oil and adapted to damp but not to prevent the oscillations of the center shaft 1 and thus of the pivot bearing 4 which are caused by the unbalance of the rotating center shaft. The radial movements of the pivot bearing 4 press the tongues 8b of spring 8 successively in the outward direction whereby the tongues are placed under tension and tend to return the bearing 4 to its central position. This centering effect of the tongues starts as soon as the pivot bearing acts upon one of the tongues, and this effect is at first very small but it then increases in accordance with the spring characteristic of the tongue. The other tongues which at this time are inactive since they are not pressed outwardly by the pivot bearing will not be affected by the centering tongues and thus remain practically stationary. This centering device therefore operates very accurately and reliably and prevents the formation of dangerous virbations, especially since the basket spring 4 may be made very accurately of the most suitable material and the tongues may also be very accurately guided by the part 6c of the supporting plug. The required centering properties of the assembly may be varied in accordance with the operating conditions and the size of the spindle by making the tongues of suitable dimensions so as to have the required spring characteristic. The centering properties may also be aected by varying the size of the play of the pivot bearing within the basket spring.

If desired, the resilient tongues may also be bent so as to be under initial tension when the spring is installed, for example, by extending conically toward the inside, as shown by the tongues Sbl in FIGURE 4. When the spring is installed, these tongues will also engage upon the part 6c in the manner as shown in FIGURE l, but with a certain initial tension which is determined by the distance of movement of the tongues from their released position as shown in FIGURE 4 to their position in which they engage upon the part 6c. The centering effect of the spring according to FIGURE 4 begins immediately as soon as the pivot bearing 4 deliects against the ends of the spring tongues and with a centering strength in accordance with the initial tension of the tongues. The frictional forces on the support of the pivot bearing 4 are determined by the contact pressure between this bearing and the supporting plug 6 or the intermediate plate 7, that is, primarily by the weight of rotary parts of the spindle. The oil-immersed coil 9 which acts with a small radial pressure upon the bushing 5 and the inner wall of housing 3 will not affect this contact pressure or only at a very small degree. The movement of coil 9 in the upward direction is substantially prevented by the spacing tube and in the downward direction by a spacing ring 10a which, when the different parts of the spindle are assembled, is preferably still spaced at a certain distance from the lower end of coil 9.

FIGURE 5 illustrates a modification of the intermediate disk 57 which is located between the pivot bearing 54 and the supporting plug 56 and provided with convex contact surfaces which are preferably hardened. Such a hardened steel disk with convex contact surfaces or with plane surfaces as shown on the disk 7 in FIGURE 1 may be produced with great accuracy and may in addition be treated so that its surfaces will have the best possible gliding properties and be hardly affected by wear. Although steel disks with convex contact surfaces on both sides have to bear higher specific surface pressures than plane disks, they permit certain rolling motions which improve the radial moveability of the pivot bearing within certain limits. Since this concave disk is guided with a clearance between the tongues S8b of basket spring 58, it can follow the radial movements of the pivot bearing by carrying out rolling motions in which the distance between the end surface 54a of the pivot bearing and the supporting surface 56]c of the supporting plug increases when the deection 0f the bearing increases which facilitates the return of the pivot bearing to its central position. If the radial deflections of this bearing increase beyond a certain extent, a sliding friction will be produced between the bearing and the intermediate disk. The annular surface 56g of the supporting plug also supports the outer spire of the oil-immersed damping coil 59.

According to the further modification of the invention as illustrated in FIGURE 6, a hardened steel ball 67 is provided between the end surface of the hardened pivot bearing 64 and the hardened supporting plug 66 and is guided with a small clearance between the radially resilient tongues of basket spring 68. The radial deflections of the pivot bearing therefore cause primarily only a rolling friction between the ball 67 and the pivot bearing and the supporting plug.

FIGURES 7 and 8 illustrate another modification in which between the pivot bearing 54 and the supporting plug 56 a ball bearing 57a is inserted which consists of three balls 57e which are guided in three apertures which are provided in a radially symmetrical arrangement in a cage disk 57b. The pivot bearing 54 is centered by a basket spring 58 in the same manner as shown in FIGURE 5.

According to FIGURE 9, the pivot bearing 74 is supported directly on the hardened supporting stud 76 which has on its lower end a wide flange 76a which lits exactly centrally into the bearing housing and rests flush on the bottom thereof. The basket spring 78 is clamped to the lower end of the wall of the housing and also rests on the flange of the supporting plug 76. Contrary to the basket spring as shown in FIGURE 2, this basket spring is preferably made of a tube of spring steel. The spring tongues 7811 may be very accurately stamped out and bent by `means of special tools and engage upon the upper part of the supporting plug 76 with such an initial tension as may be necessary to attain the desired centering effect. The ends of the spring tongues surround the pivot bearing with a small clearance.

According to FIGURE l0, the hardend supporting plug 86 is flanged into the bearing housing 83. The tongues 88b of the basket spring again engage upon the supporting plug and the pivot bearing similarly as shown in FIGURE 1. Above their points of engagement with the supporting plug, these spring tongues are provided with extensions 88e which are bent outwardly to such an extent as to project freely into the oil chamber between the pivot bearing and its tubular extension and the inner wall of the housing and are adapted to effect at least partly the damping of the spindle vibrations. An effective damping action may already be attained if the tongue extensions 88C project at least up to the upper end 84a of the pivot bearing. Especially in spindles which are not subjected to very high stresses, it may then be unnecessary to install additional damping means of a known type, for example, an oilimmersed coil, between the pivot bearing or the bushing and the wall of the housing or it may then suffice to install very simple additional `damping means, for example, a rubber sleeve. These additional damping means (not shown) may be installed independently of the basket spring or they may be connected to the extensions of the spring tongues.

According to FIGURE 11, the basket spring 98 is firmly secured to the pivot bearing 94 and its spring tongues 98h extending in the downward direction embrace the supporting plug 96. In a reverse arrangement to that as shown in FIGURE l, the spring tongues 98b may also in this case engage with more or less initial tension upon a separate wall surface 94a of the pivot bearing. Bushing is prevented from turning in a similar manner as shown in FIGURE 1 by a guard ring 95h, and a damping element 99 is also installed between the bushing 95 and the wall of the housing.

According to FIGURE 12, the connecting element consists of a tube 108 of plastic which is secured to the pivot bearing 104 by an initial tension and is additionally locked thereon by projections 108a engaging into corresponding recesses in bearing 104. The lower part of the plastic tube 108 is divided into tongues 108 by slots which preferably increase in width in the downward direction. For a spindle which is not to be subjected to high stresses, these slots may be omitted, provided the wall of the tube is designed and of such dimensions that the desired resilience and centering effect will be attained.

FIGURE 13 shows a construction in which the pivot bearing 114 is guided with a small clearance in the bushing 115 and prevented from turning and from shifting upwardly by a guard ring 115:1. Bushing 115, in turn, is prevented from turning in a similar manner as shown in FIGURE 1 by a guar-d ring 11511. The pivot bearing is supported via the bushing 115 on the intermediate disk 117 which is secured to supporting plug 116. The bracket spring 118 serving as a connecting element embraces the bushing 115 by means of its spring tongues 118b which are slightly curved inwardly. Between these curved centering tongues 118b the basket spring is provided with straight tongues 118e which projects upwardly slightly beyond the tongues 11817 and serve as a support for the damping element 119.

FIGURES 14 and l5 show a construction in which the pivot bearing for the center shaft 121 is divided and composed of a bearing plate 124:1 and a bearing sleeve 124b. The lower cylindrical part of the center shaft 121 is provided with an end surface 121a which is Slightly rounded, preferably with a radius of 25 to 35 mm., and rotates under the axial pressure of the rotary spindle parts on the bearing plate 124a. The radial pressure which is exerted by the center shaft is taken up by the bearing sleeve 124b which is supported on the bearing plate 124a and is guided within the oil-immersed coil129. The supporting plug 126 serves at the same time as a cap for closing the lower end of housing 123. The 'basket spring 128 which is mounted on the supporting plug 126 and serves as a connecting element surrounds the reduced lower part 124C of bearing sleeve 124b. Bearing plate 124a rests on the supporting plug 126 and is guided with a small radial clearance within the basket spring 128. The oil-immersed coil 129 is prevented from shifting excessively in the downward direction by a spacing ring 130a and in the upward direction by a spacing tube 130 which is inserted tightly into the housing 123. The inwardly bent tabs 130b on this spacing tube extend into apertures 125a in the guard tube 125 which is made of plastic and the upper end of which is radially guided in the spacing tube 130, while its central and lower parts are guided with a slight clearance in the oil-immersed coil 129. On its lower end, guard tube 125 is provided with projections 125b, as also shown in FIGURE 15, which project inwardly into slots 124b in bearing sleeve 124b and rest on the lower ends of these slots. Guard tube 125 and spacing tube 130 thus prevent the sleeve 124b from turning within housing 123 and also limit its axial movement in the upward direction. Bearing sleeve 124b is further provided with apertures 124e of a sufficient size to permit an adequate flow of oil.

FIGURE 16 shows a spindle construction in which for absorbing the axial impacts of the center shaft a resilient element in the form of a ring 137 of a resilient plastic, for example, polyethylene, is inserted between the bearing plate 134a and the supporting plug 136. This construction is of advantage particularly when the spindle is subjected to considerable impact stresses in its axial direction.

The projection 136f on the supporting plug guides a ring 137 and toegther with bearing plate 134a defines a small solt S of a width of, for example, 0.6 to 1 mm. which determines the extent of the resilient compression of ring 137 in the axial direction and insures that the center shaft cannot be excessively pressed in the downward direction. Ring 137 will thereby also be prevented as much as possible from being permanently deformed. Bearing sleeve 13417 is pressed tightly into tube 135 which, in turn, is guided within the damping element 139. The means for preventing tube 135 from turning in housing 133 are not illustrated and are similar to those shown in FIGURE 14.

FIGURE 17 Shows the bearing plate 144a in the form of a projection on the supporting plug 146 which projects into the bearing sleeve 144b which rests on the supporting plug. The projection 144a may have such a diameter that it will also limit the radial movements of bearing sleeve 144b and thus also of the damping elelment 149. The bearing plate 144a may ,also be provided in the form of a hardened disk which is separate from the supporting plug 146, has plane parallel surfaces on both sides, rests on the supporting plug 146, and projects into the bearing sleeve .144b like the projection 144:1.

FIGURE 18 finally shows a spindle construction in which the bearing plate 154a is mounted within the supporting plug. Bushing 154b rests on bearing plate 154a and is inserted with a small radial clearance into a damping sleeve 155. The lower end of this damping sleeve is provided with an inwardly directed flange 155e which supports the damping sleeve on the supporting plug 156. The center shaft 151 has a plane lower end surface which is adapted to rotate on the slightly convex contact surface of bearing plate 154a.

Although my invention has been illustrated and described with reference to the preferred embodiments thereof, I wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications as would be obvious to one with normal skill in the pertinent technology.

Having thus fully disclosed my invention, what I claim is:

1. In a spindle assembly for a spinning or twisting machine having a tubular bearing housing, a center shaft within said housing, `a collar bearing mounted in said housing near the upper end thereof for radially supporting said shaft, a pivot bearing in said housing separate from said collar bearing for supporting the lower end of said shaft, a supporting element within .and rigidly secured to the lower end of said housing for maintaining said pivot bearing in a fixed position in the axial downward direction within said housing but permitting said pivot bearing to move in radial directions within said housing, and means for restraining the radial movements of said pivot bearing, the improvement according to which said restraining means comprise a tubular connecting element, said pivot bearing and said supporting element comprising two separate normally coaxial rnezmbers axially adjacent to each other within said housing, said connecting element having one end rigidly connected to one of said members and a radially resilient part projecting from said end toward the other member and at least partly surrounding and substantially engaging with said other member.

2. A spindle assembly as defined in claim 1, wherein said supporting element comprises a plug-shaped member secured to the lower end of said housing and having a central stud axially projecting into said housing, said connecting element surrounding said stud and at least the lower end of said pivot bearing.

3. A spindle assembly as defined in claim 2, wherein said one end of said connecting element is rigidly connected to the wall of said housing and rests on said plug-shaped member, while said radially resilient part surrounds and substantially engages with and guides said pivot bearing.

4. A spindle assembly as defined in claim 1, wherein said radially resilient part engages with resilient tension radially upon said other member.

5. A spindle assembly as defined in claim 1, wherein said connecting element consists of plastic.

6. A spindle assembly as defined in claim 1, wherein said connecting element consists of a tubular basket spring having a plurality of slots each extending from one end of said spring at least to a point central of the length of said spring and peripherally spaced from each other .and defining tongues forming said radially resilient parts.

7. A spindle assembly as defined in claim 2, wherein said pivot bearing and said plug-shaped member have substantially plane parallel end surfaces facing each other and each extending at a right angle to the axis of said housing, and further comprising an intermediate member within said tubular `connecting element 4between said end surfaces and having an outer diameter slightly smaller than the inner diameter of said radially resilient part of said tubular connecting element so as to have .a small radial play therein.

8. A spindle assembly as defined in claim 7, wherein said intermediate member consists of a hardened disk having plane parallel opposite surfaces.

9. A spindle assembly as defined in claim 8, wherein said intermediate member consists of a hardened disk having convex opposite surfaces.

10. A spindle assembly as defined in claim 7, wherein said intermediate member consists of a hardened ball.

'11. A spindle assembly as defined in claim 7, wherein said intermediate member consists of a cage disk having said outer diameter and a plurality of apertures therein, and a hard ball within each of said apertures and guided by the wall thereof 12. A spindle assembly as defined in claim 6, wherein said supporting element comprises a plug-shaped lmember secured to the lower end of said housing and having a central stud axially projecting into said housing, said stud having an annular recess dividing the outer surface of said stud into an upper and a lower section, the unslotted part of said 'basket spring surrounding and being clamped tightly upon said lower section, the free ends of said tongues substantially surrounding and engaging with said pivot bearing, and a part of each of said tongues intermediate said ends and said unslotted part engaging with tension upon said upper section.

13. A spindle assembly as defined in claim 12, wherein said lower section of said stud has another annular recess therein, said unslotted part of said spring having at least one resilient locking projection extending into said other annular recess so as to prevent said spring from moving in the axial direction of said stud.

14. A spindle assembly as defined in claim 2, wherein said plug-shaped member is a turned part and comprises a plug part inserted into the lower end of said housing and closing said end, and .a central stud of a smaller diameter than and integral with said plug part and extending into said housing.

15. A spindle assembly as defined in claim 14, wherein said plug part comprises a circular plate having a diameter substantially equal to the outer diameter of the lower end of said housing and covering the same, said stud being integral with said plate and projecting therefrom and an annular part around and radially spaced from said stud and integral with said plate, the outer surface of said annular part engaging with the inner wall surface of said housing, and a damping element between the inner wall of said housing and at least said pivot bearing, the upper end surface of said annular part being adapted to engage with the lower end of said damping element and to support the same.

16. A sprindle assembly as defined in claim 1, wherein said connecting element is provided with supporting surfaces, and further comprising a damping element between the inner Wall of said housing and at least said pivot bearing and supported on said supporting surfaces.

17. A spindle assembly as defined in claim 1, wherein said pivot bearing is radially spaced from the wall of said housing so as to define a chamber, and further comprising radially resilient damping means secured to said connecting element and freely projecting upwardly into said chamber at least up to the level of the upper end of said pivot bearing ywhen said pivot bearing is in its normal central position within said housing.

18. A spindle assembly as defined in claim 6, wherein said pivot bearing is radially spaced from the wall of said housing so as to define a chamber, at least some of said tongues partly surrounding and substantially engaging with said pivot bearing, and at least some of said tongues having extensions projecting upwardly into said chamber at least up to the level of the upper end of said pivot bearing when said pivot bearing is in its normal central position within said housing and serving as resilient damping means for said pivot bearing when the latter is moved out of said central position.

19. A spindle assembly as defined in claim 2, wherein said pivot bearing comprises a bearing plate on the upper end of said stud and engaging with the lower end of said center shaft for taking up the axial downward pressure of said shaft, and a bearing sleeve separate from said bearing plate and surrounding a part of said shaft above said bearing plate and. movable independently thereof and adapted to take up the radial pressures of said center shaft, said tubular connecting element also surrounding said bearing plate and at least the lower end of said bearing sleeve and connected to said sleeve for supporting the same.

20. A spindle assembly as defined in claim 19, further comprising a resilient buffer between and engaging with said bearing plate and the upper end of said stud.

21. A spindle assembly as defined in claim 20, wherein said bearing plate and said stud form two separate members, one of said members having at least one projection thereon extending toward the other member and normally being spaced by said buffer at a small axial distance from said other member and adapted to engage with said other member when said buffer is axially compressed, thus limiting the compressibility of said buffer.

22. A spindle assembly as defined in claim 19, wherein said bearing plate has opposite plane parallel surfaces and an outer diameter slightly smaller than the inner diameter of said tubular connecting element surrounding said plate so as to have a small radial play within said connecting element.

23. A spindle assembly as defined in claim 19, wherein said connecting element consists of a basket spring connecting said stud in said bearing sleeve and surrounding the lower end thereof and engaging thereon substantially without tension, said bearing sleeve resting on the upper surface of said bearing plate.

24. A spindle assembly as defined in claim 19, further comprising a damping element between the inner wall of said housing and said bearing sleeve and surrounding and directly engaging with said sleeve.

25. A spindle assembly as defined in claim 24, further comprising a tubular bushing around but radially spaced from said center shaft and disposed above said hearing sleeve and nonrotatably connected to said housing, the adjacent ends of said bushing and said bearing sleeve having associated projections and recesses engaging with each other so as to prevent said bearing sleeve from turning and to limit its axial moveability within said housing.

MARTIN P. SCHWADRON, Primary Examiner. F. SUS-KO, Assistant Examiner. 

